Marijuana use among USA pregnant women increased from 4.2 percent in 2009 to 7.1 percent a year ago.
In many states, medical marijuana can be prescribed for treating conditions including severe nausea and pain - both of which may affect pregnant women - but the American College of Obstetricians and Gynecologists recommends women stay away from weed if they want to have a baby. "In aggregated 2002-2012 data, 14.6 percent of US pregnant adolescents reported past-month use". For women in the 18 to 24 age bracket, marijuana usage spiked from 12.5 percent to 21.8 percent in that same period.
According to the CDC, doctors caution that marijuana's effects on a fetus are not clear but it could include low birth weight and developmental problems.
Medical use of marijuana is already legal in California, which was one of the first states to legalize marijuana for that use two decades ago.
"Marijuana is [one of] the most commonly used illicit drugs during pregnancy, and its use is increasing", the study says. After four out five states that tried to pass a measure succeeded in 2016, no additional states legalized it in 2017.